1. Field of Invention
The present invention relates to a safety device for combination articulated vehicles, such as semi-trailer trucks, full-trailer trucks, trains, and subways. More particularly, the present invention relates to a damping system placed between the lead and trail vehicles in a combination articulated vehicle that is designed to absorb the kinetic energy of the trail vehicle during impact.
Generally, combination articulated vehicles are two or more vehicles attached together to form a chain of vehicles and are used primarily to transport cargo or passengers. One example of a combination articulated vehicle is a semi-trailer truck in which a truck is coupled to a trailer. By attaching an additional trailer to the semi-trailer truck, the combination articulated vehicle becomes a full-trailer truck made up of a chain of three or more vehicles. In like manner, trains and subways are combination articulated vehicles made up of engines and cars coupled together in a chain of vehicles. In order to simplify the discussion, the vehicles in a combination articulated vehicle are taken two at a time and referred to as the lead vehicle and the trail vehicle. As the name suggests, the lead vehicle is the vehicle in front when the combination articulated vehicle is moving in the forward direction (e.g. the truck in a semi-trailer truck). Similarly, the trail vehicle is the towed vehicle in a combination articulated vehicle (e.g. the trailer in a semi-trailer truck). One aspect of all combination articulated vehicles is that they must have a gap between the lead and trail vehicles to permit the combination articulated vehicle to turn.
Accidents involving these vehicles often result in extensive property damage, injury, and loss of life. One reason accidents involving combination articulated vehicles are particularly destructive is due to the substantial weight carried in the trail vehicle. When moving, this increased weight in the trail vehicle greatly increases the total kinetic energy of the combination articulated vehicle. Thus, when a combination articulated vehicle collides with another object, the kinetic energy of the trail vehicle transfers to the lead vehicle thereby increasing the kinetic energy of the collision. The increased kinetic energy subjects the operator of the combination articulated vehicle to great accelerations. Additionally, the increased kinetic energy results in greater collision impact forces causing greater damage. The addition of the increased impact forces endangers both the operator of the combination articulated vehicle and others involved in the collision.
2. Related Art
Combination articulated vehicle damping systems are known to the prior art. Illustrative of such systems is U.S. Pat. No. 3,950,011 that issued to Yamanaka on Apr. 13, 1976. However this system does not provide a truly simple remedy for the problem of absorbing the kinetic energy of a trail vehicle during the collision of a combination articulated vehicle. The system shown in Yamanaka teaches the use of a friction plate between the trailer and truck of a semi-trailer truck combined with plastic deformation of the frame of the truck to provide damping. Also, Yamanaka reveals the use of a metal rod designed to plastically deform and absorb kinetic energy during a collision. Further, Yamanaka shows the use of pneumatic and hydraulic cylinders to absorb the kinetic energy of the trailer.
Although Yamanaka provides a safety damping system for combination articulated vehicles, its application requires destruction of the truck frame by design. The design concentrates the load at a narrow point and, thereby, mandates extensive strength and weight of the truck frame; and the design provides for limited damping travel. In addition, implementation of its damping device requires extensive redesign of both the truck and the trailer and may not yield dependable results if oil or water accumulates on the friction plate. Also, Yamanaka has no application to other combination articulated vehicles such as trains and subways.
A related effort is U.S. Pat. No. 3,633,934 that issued to Wilfert on Jan. 11, 1972. Wilfert teaches the use of a piston to deform an energy dissipating medium held within a cylinder to prevent transmission of collision forces to the passenger compartment of a passenger automobile. While not related to combination articulated vehicles, but to passenger automobiles, Wilfert aids in understanding the present invention.
In view of the known combination articulated vehicle damping system, the present invention represents an improvement to provide a damping system that is easily applied to existing combination articulated vehicles with little modification. Additionally, the present invention provides a low cost, easily installed and maintained damping system that is more efficient than prior efforts. Also, the present invention provides damping without destroying the combination articulated vehicle components, as prior efforts do, thereby allowing for lower cost of repair.